Monday, April 14, 2008
1. Chapter 17 Quiz
2. Notes Section 18.1 – Oxidation-Reduction
3. Homework – Reading Analysis – Section 18.1
Types of Reactions
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What were the types of reactions we
talked about back in chapter 8?
Precipitation
Acid-base
Combustion
Synthesis
Decomposition
Classify the reaction type for
each of the following:
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Forest fire
Rusting steel
Gasoline in car
Metabolism of food
Batteries
All of these are types of oxidation/reduction
reactions.
Oxidation
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What do you think happens in these reactions?
What does the word sound like?
Called oxidation because ‘O’ is added to element
Originally used to describe combustion- reaction
of substances with oxygen in the air
When substances lost oxygen, they were reduced
in mass  called reduction reactions
Metal/Nonmetal
Reactions
o
o
+1
-1
2Na(s) + Cl2(g)  2NaCl(s)
Na
e-
Cl

Na+Cl-
Drawing
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Recall how we drew this transfer of
electrons.
An electron is transferred from the
sodium to the chlorine
Oxidation-Reduction
Reactions
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Reactions in which one or more
electrons are transferred
Also called Redox reactions
Oxidation is defined as the loss of
electrons
Reduction is defined as the gain of
electrons
Oxidation / Reduction
OIL RIG – Oxid. Is Loss, Reduc. Is Gain
LEO the Lion goes GER –
Lose Electrons Oxidation
Gain Electrons Reduction
Oxidation / Reduction
4Fe + 3O2  2Fe2O3
What is oxidized? What is reduced?
Zn + Cl2  Zn2+ + 2ClPractice Problem 18.1
2Cu + O2  2CuO
2Cs + F2  2CsF
Oxidation/Reduction
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Do metals gain or lose electrons?
Are they oxidized or reduced?
Do some metals lose electrons more
easily than others?
If you put Cu(s) in Mg(NO3)2, will Cu lose
e- and Mg gain them to become Mg?
– Which metal wants to get rid of e- more?
Will a Reaction Occur?
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Magnesium wants to get rid of
electrons more so it won’t take them
away from copper
How do we know?
Electronegativities page 403
Mg 1.2, Cu 1.9
How about Mg and Fe(NO3)2?